In polar regions such as Northern Canada and Alaska, an enchanting display of…

Concept: Auroras (Aurora Borealis in the Northern Hemisphere) are a space-weather phenomenon: the Sun continuously emits a stream of charged particles (electrons and protons) called the solar wind, and Earth's magnetic field channels these particles toward the magnetic poles rather than letting them strike the whole globe.

Application: Near the poles, magnetic field lines converge and funnel the charged particles down into the upper atmosphere (roughly 100 to 300 km altitude). There they collide with atmospheric gases, oxygen and nitrogen, transferring energy that excites the gas molecules' electrons. As these electrons fall back to lower energy levels, they release the energy as light: oxygen gives greenish and red glows, nitrogen gives blue and purple glows, producing the shifting curtains of colour seen over Northern Canada and Alaska.

• cold temperature near the poles: low temperature alone does not emit light; it explains the region's ice and climate, not a glowing display of colours.

• atmospheric currents due to pressure difference: pressure-driven winds move air masses but do not excite gas molecules to emit light; that needs an external energy source.

• oceanic pressure variations near the poles: ocean pressure affects currents and sea level, not atmospheric light emission at 100 plus km altitude, far above the ocean's influence.

Cross-check: The mechanism also explains why the display is confined to polar regions: the magnetic field lines that funnel the charged particles converge specifically at high latitudes, so places far from the poles rarely see it, consistent with the stem's framing of polar regions such as Northern Canada and Alaska.

Answer: The aurora is produced by charged solar particles trapped and funneled by Earth's magnetic field into the polar atmosphere, where they excite atmospheric gases to glow.